Relocate RemoteClusterService methods only used in tests. (elastic#132037)

This change eliminates or moves the following methods from
RemoteClusterService:
  isCrossClusterSearchEnabled()
  isRemoteNodeConnected()
  isRemoteClusterRegistered()

This is part of an effort to reduce the API surface area
of RemoteClusterService.

Relates: elastic#131894, elastic#131948

Author: JeremyDahlgren

server/src/main/java/org/elasticsearch/transport/RemoteClusterService.java

@@ -172,17 +172,6 @@ public DiscoveryNode getLocalNode() {
         return transportService.getLocalNode();
     }
 
-    /**
-     * Returns <code>true</code> if at least one remote cluster is configured
-     */
-    public boolean isCrossClusterSearchEnabled() {
-        return remoteClusters.isEmpty() == false;
-    }
-
-    boolean isRemoteNodeConnected(final String remoteCluster, final DiscoveryNode node) {
-        return remoteClusters.get(remoteCluster).isNodeConnected(node);
-    }
-
     /**
      * Group indices by cluster alias mapped to OriginalIndices for that cluster.
      * @param remoteClusterNames Set of configured remote cluster names.
@@ -258,13 +247,6 @@ public Set<String> getConfiguredClusters() {
         return getRegisteredRemoteClusterNames();
     }
 
-    /**
-     * Returns <code>true</code> iff the given cluster is configured as a remote cluster. Otherwise <code>false</code>
-     */
-    boolean isRemoteClusterRegistered(String clusterName) {
-        return remoteClusters.containsKey(clusterName);
-    }
-
     /**
      * Returns the registered remote cluster names.
      */

server/src/test/java/org/elasticsearch/transport/RemoteClusterClientTests.java

@@ -40,6 +40,7 @@
 import static org.elasticsearch.test.NodeRoles.removeRoles;
 import static org.elasticsearch.transport.AbstractSimpleTransportTestCase.IGNORE_DESERIALIZATION_ERRORS_SETTING;
 import static org.elasticsearch.transport.RemoteClusterConnectionTests.startTransport;
+import static org.elasticsearch.transport.RemoteClusterServiceTests.isRemoteNodeConnected;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.instanceOf;
 
@@ -95,7 +96,7 @@ public void testConnectAndExecuteRequest() throws Exception {
                 service.acceptIncomingRequests();
                 logger.info("now accepting incoming requests on local transport");
                 RemoteClusterService remoteClusterService = service.getRemoteClusterService();
-                assertTrue(remoteClusterService.isRemoteNodeConnected("test", remoteNode));
+                assertTrue(isRemoteNodeConnected(remoteClusterService, "test", remoteNode));
                 var client = remoteClusterService.getRemoteClusterClient(
                     "test",
                     threadPool.executor(TEST_THREAD_POOL_NAME),
@@ -172,7 +173,7 @@ public void testEnsureWeReconnect() throws Exception {
                 // the right calls in place in the RemoteAwareClient
                 service.acceptIncomingRequests();
                 RemoteClusterService remoteClusterService = service.getRemoteClusterService();
-                assertBusy(() -> assertTrue(remoteClusterService.isRemoteNodeConnected("test", remoteNode)));
+                assertBusy(() -> assertTrue(isRemoteNodeConnected(remoteClusterService, "test", remoteNode)));
                 for (int i = 0; i < 10; i++) {
                     RemoteClusterConnection remoteClusterConnection = remoteClusterService.getRemoteClusterConnection("test");
                     assertBusy(remoteClusterConnection::assertNoRunningConnections);
@@ -286,7 +287,7 @@ public void testQuicklySkipUnavailableClusters() throws Exception {
                 );
 
                 try {
-                    assertFalse(remoteClusterService.isRemoteNodeConnected("test", remoteNode));
+                    assertFalse(isRemoteNodeConnected(remoteClusterService, "test", remoteNode));
 
                     // check that we quickly fail
                     if (randomBoolean()) {
@@ -325,7 +326,7 @@ public void testQuicklySkipUnavailableClusters() throws Exception {
                         () -> safeAwait(listener -> client.getConnection(null, listener.map(v -> v)))
                     )
                 );
-                assertTrue(remoteClusterService.isRemoteNodeConnected("test", remoteNode));
+                assertTrue(isRemoteNodeConnected(remoteClusterService, "test", remoteNode));
             }
         }
     }